Expansible screw



J. A. BILTERMAN.

EXPANSIBLE SCREW. APPLICATION FILED DEC. 13, 1920.

1,392,108. P en e ep 27,19 1.

2 SHEETS-SHEET 2- B ATTORNEY PATENT OFFICE.

JOHN a nrn'rmm, or ALIBIA, IOWA.

1 Exrmsnama SCREW.

To all whom it may concern: 7

Be it known that I, JOHN A. BILTERMAN, a citizen of the United States,residin at Albia, in the county of Monroe and tate of Iowa, haveinvented new and useful Improvements in Expansible Screws, of which thefollowing is a specification.

It is the object of the present invention to produce an expansible woodscrew whereby the employment of the usual screw driver will be entirelydispensed with.

A further object is the production of an improved Wood screw designed tobe received in a hollow which has been previously bored that has itsentering end tapered and slitted and provided with teeth of a particularand peculiar formation, said screw having a central opening therethroughdesigned for the reception of a removable pin or key, which, when forcedthrough the bore, will spread the slitted end of the screw, causing theteeth to bite into the wood provided by the opening and, incident to thepeculiar formation of the said teeth, to draw the screw further into theopening.

The foregoing, and other objects which will appear as the nature of theinvention is better understood, may be accomplished by a construction,combination and operatlve arrangement of parts, such as is disclosed bythe drawings which accompany In the drawings .Figure 1 is a view of ascrew-constructed in accordance with this invention, inserted in a boredopening, the wood plates to be connected by the screw being in section.

Fig. 2 is a substantially similar view, except that the screw is shownin sectlon and expanded, the expanding pin or key being in elevation.

Fig. 3 is an end view of the screw lookmg toward the threaded portionthereof.

Fig. 4 is a sectional view on the line 44.-

and which form part of this application.

of Fig 1. I

Fig. 5 is a perspective view of the key. Fig. 6 is a plan view lookingtoward the head of the screw when arranged in' the positionillustratedin Fig. 1.

Fig. 7 is a similar view looking toward the head of the screw, with thekey therein as illustrated in Fig. 2.

Fig. 8 is an end view of the screw when the split or segmental. endthereof is sgread. qReferrin now' to the drawmgs 1n etail, the" numera s1 and 2 indicate two wooden Specification of Letters Patent.

the openings 3,

plates to be connected in accordance with this nventlon. At the pointswhere the connect- Patented Sept. 27, 1921. Application filed December13, 1920. Serial No. 430,330.

Each of the elements 5 has its body portion or shank of a size to besnuglyrecewed in its outer end provided with a head 6 Whose inner wallis flared inwardly, as at 7, the said head bein snuglyreceived 1n thereamed portion 4. he body or shank 5, at a point adjacent to the loweror outer end thereof is arranged at an inward inclination, as indicatedby the numeral 8. On this reduced portion the body. is provided withteeth 9 formed by annular flanges which gradually decrease in diameterfrom the outer to the inner plate. The teeth, it will be noted are notof a spiral formation, and each tooth is independent of the other. Allof the teeth, however, have their peripheral edges in longitudinalalinement, and'each is of a width approximately equaling that of thecross sectional diameter of the body or shank 5 of the device. Each ofthe circumferential teeth is beveled, on the face nearest the head in adirection away from the head, as at 10 and terminates in a sharpenedpoint or edge.- The inclined or flared end 8 of the shank. 5, for adistance slightly greater than the space occupied by the disk like teeththereon, is slitted longitudinall the said slits being arranged rightangularl j with respect to each other. These slits are indicated by thenumeral 11' and divide the flared portion 8 ofthe shank into segmentalsections, and on each of these sections the disk-like teeth 10 areformed. If desired, the teeth need not entirely surround the flaredportion of the shank, but may be in the nature of spurs arranged inseries on each of the segmental portions 12 of the shank. This lastconstruction is preferable and is illustrated by the drawings.

The shank has a round bore 13 which has its lower portion flaredinwardly, as at 14, at the flared portion 8 of the shank. The top orhead 6 of the shank has a round opening 15 which terminates in a.straight shoulder 16 at the juncture of the shank and head;

The spreader member is in the nature of faces thereof, said shank havinga bore diameter than the flange, extending outward of the flange. 4

They key is inserted-in the bore 13 of the shank, until the lower androunded end 20 thereof contacts with the flared portion 14 of the bore13. Thereafter the key is subjected to forcible contact by a hammer orthe like so that the key will spread the seg-' mental portions 12 at thebeveled end of the shank, away from each other, causing the said beveledportions to contact with the walls of the opening 3 in the chamber orplate 1, and also causing the teeth 9 to enter the said chamber. Bybeveling the teeth, as-

vabove described, the inclined portions thereof, when entering thechamberl will cause the shank to be moved longitudinally in an inwarddirection through the opening 3, and thus cause the beveled head to bindagainst the beveled wall provided by the reamed portion 4 in the outerplate or chamber 2. he socket portion 15 in the head 6 of the shank isof a sufficient area to permit of a suitable instrument 'being insertedtherein to grip the head 19 of the pin 17 and thus remove the pin.

The pin'remains in the screw as long as the screw is expanded, but iswithdrawn from the screw when the screw is to be removed. Fromexperience, I have found that the best results are obtained by theemployment of flexible metal screws, as such metal permits ofcontraction at the slit portion thereof so that the same is easilyremoved when the pin is withdrawn.

Having described the invention, I claim 1. A wood screw designed to bereceived in an opening bored through plates to be connected, including ashank which is snugly received in the opening, a head on the one end ofthe shank, and an inwardly flared portion on the opposite end of saidshank, said flared portion being slotted longitudinally and providedwith spaced teeth all of an equaldiameter and all beveled from theirinner to their outer edges upon the inner 2. In combination with twowooden plates to be connected, and each of said plates having boredopenings for the connectin means and the outer plate being reame aroundthe o enings, of an expanslble wood screw inclu iiig a shank designed tobe freely received in each of the openings, a beveled head on the shankto be received in the reamed portions of the openings, the

body of the shank being flared inwardly from the end thereof oppositethat provided with thehead and being slit longitudinally for a distanceslightly greater than the flared portion of the shank dividing saidflared portion into segments, each of said segments having spaced teeththereon which gradually decrease in length from the outer to the innertooth, whereby the edges of all of the teeth arein alinement with eachother and in alinement with the straight portion of the shank, saidshank having a longitudinal bore therethrough which is flared inwardlyat the flared end of the shank, the head of the shank having a socketsurrounding the bore, a key for insertion in the bore having a flangeadjacent to its outer end and an inwardly inclined head projecting fromthe flange, and of a less diameter than the flange, said key designed tobe inserted in the bore and to be forced against the segmental portionsof the shank to spread the latter against the wall of the opening and toforce the teeth on the segments into the wall provided by the opening,and by virtue of the shape of the said teeth to move the shanklongitudinally through the opening to bring the head thereof in tightengagement with the reamed wall surrounding the opening.

In testimonywhereof I aflix my signature.

JOHN'A. BILTERMAN.

